The goal of the project is to elucidate the cellular mechanisms of early visual processing in the primate eye. Light-evoked electrical signals will be measured in single photoreceptors and bipolar cells in primate retina. The results will be used to make quantitative comparisons to human visual abilities and limitations. The objective is to determine how the characteristics of the neural mechanisms of the eye shape our visual experience. The application contains experiments to address response characteristics of (1) photoreceptors and (2) bipolar cells, the first integrative stage in information processing in the retina. Studies of photoreceptors are designed to determine how accurately photoreceptors detect light, how the cells' reliability limits the reliability of light detection by the human eye, and whether photoreceptors inhibit neighboring photoreceptors. Studies of bipolar cells are designed to determine which photoreceptors send information to which bipolar cells, how accurately the bipolar cells signal light stimuli, how bipolar cell sensitivity is altered by light adaptation, and how these alterations compare with light-adaptive changes in human vision as a whole. The studies also will address the reason for having so many bipolar cell types, and what their separate roles are in information processing. These studies are significant because they will provide quantitative information for understanding visual processing, for use in modeling, and for interpreting the clinical ERG and enhancing its utility in diagnosing retinal pathology and monitoring effects of therapeutic interventions.